Slit scanning exposure apparatus

ABSTRACT

The improved slit scanning exposure apparatus has a variable slit assembly that is provided in proximity with the exposing zone and which is composed of two slit plates movable independently of each other in synchronism with the scannning speed. The apparatus may additionally have a color filter that can be inserted into the optical path of reflected light from the image on a document in the scanning direction. The apparatus is capable of preventing flare from being admitted through an exposure slit to a light-sensitive material on the exposure position when it is being exposed from light reflected from the document image. In addition, the apparatus enables more than one document image to be edited into a single image and permits the color filter to be inserted into the optical path of reflected light without causing unevenness in colors.

BACKGROUND OF THE INVENTION

The present invention relates to a slit scanning exposure apparatussuitable for use with various types of copiers, printers, presses, etcMore specifically, the present invention relates to a slit scanningexposure apparatus that is capable of effective light adjustment, inparticular, the adjustment of the quality of light by means of colorfilters, with satisfactory color and density reproduction. The presentinvention further relates to a slit scanning exposure apparatus that iscapable of preventing entrance of flare at the exposure position and bywhich editing of more than one document image is possible as required.

Exposure apparatus for use with various types of copiers, printers,presses, etc. commonly employ slit scanning exposure for severaladvantages it has over one-shot exposure of still image such as, forexample, (1) the smallness of an area to be exposed and hence the sizeof the exposure apparatus, and (2) the need to use a smaller quantity oflight from a light source.

An example of the application of a slit scanning exposure apparatus to acopier is shown in FIG. 9. A prior art slit scanning exposure apparatuscomprises basically an exposing light source 506 which illuminates adocument 504 on a platen 502 as it scans across the underside of thedocument in the direction indicated by arrow x, a mirror 508 that movestogether with the light source 506, mirrors 510 and 512 that move in thesame direction as the light source 506 at one half the speed of itsmovement, a lens unit 514 composed of such elements as imaging lenses,color filters and various types of diaphragm stop, photometric means 516for performing photometry on reflected light from the document 504during prescanning or adjustment for white balance, etc., and a shutter520 which changes the direction of the optical path L in such a way thatlight is admitted either into the photometric means 516 or onto anexposure plane 518.

In the slit scanning exposure apparatus 500, the document 504 isilluminated with the exposing light source 506 which performs scanningat a predetermined speed in the direction indicated by arrow x. Lightreflected from the document 504 (which light is hereinafter referred toas "reflected light") passes through a slit 507 and is reflected, insequence, by mirror 508 that moves together with the light source 506and mirrors 510 and 512 that move in the same direction as the lightsource 506 at one half the speed of its movement The so reflected lighttravels over the optical path L and is admitted into the lens unit 514where it is so adjusted as to be focused in a predetermined exposureposition, namely, exposure plane 518 and further adjusted for thequantity and quality of light before it passes through an exposure slit522 and is focused in the exposure plane 518 so as to scan and expose alight-sensitive material 528 which is being transported by means of tworoller pairs 524 and 526 in synchronism with the scan speed of the lightsource 506.

When the exposure is completed, the light source 506 turns off and theshutter 520 blocks the optical path L by pivoting about a fulcrum 520ato move from the position indicated by a solid line in FIG. 9 to theposition indicated by a dashed line.

In the prior art slit scanning exposure apparatus, adjustment of thequality of reflected light which is necessary to adjust the colorbalance and color densities is accomplished by means of various colorfilters that are mounted in the light source unit, lens unit or someother unit and which are selectively inserted into the optical path ofreflected light A lens unit having such color filters installed in itsinterior is shown in FIG. 10. The lens unit which is generally indicatedby 514 can be used as the lens unit in the slit scanning exposureapparatus 500 shown in FIG. 9.

The lens unit 514 shown in FIG. 10 comprises the front group 532 andrear group 534 of imaging lenses, a first color filter assembly 536having a cyan and a yellow filter, a second color filter assembly 538having a cyan and a magenta filter, a fixed diaphragm stop 540, and avariable diaphragm stop 546 having a pair of plates 542 and 544.

The reflected light travelling in the optical path L has its quantityand quality adjusted by passage through the lens unit 514. Thereafter,the reflected light passes through an exposure slit 522 located in frontof the exposure position and is focused in that position to expose alight-sensitive material 528.

To take the first color filter assembly 536 as an example, a cyan filter550C and a yellow filter 550Y are formed on a colorless and transparentglass plate 550 by evaporation or some other suitable technique and saidglass plate is then incorporated into a frame 552. A rack 554 is formedon the frame 552 which engages a motor 560 via gears 556 and 558.

When the motor 560 rotates, the frame 552 of the first color filterassembly 536 is caused to move along the length of exposure slit 522 inthe direction indicated by a double-headed arrow, namely, in a directionperpendicular to the scanning direction, and this permits either one ofthe cyan and yellow filters to be inserted into the optical path L.Stated more specifically, cyan filter 550 C is inserted into the opticalpath L if the motor 560 rotates clockwise, whereas yellow filter 550Y isinserted into the optical path L if the motor 560 rotatescounterclockwise, with the movement of either filter being parallel tothe length or longer side of the slit 522. By controlling the amount ofmotor rotation, the amount in which each filter is inserted into theoptical path L is varied to achieve proper adjustment of the reflectedlight.

The second color filter assembly 538 has the same construction as thefirst color filter assembly 536 in that a cyan filter 562C and a magentafilter 562M are formed on a transparent glass plate 562.

The prior art slit scanning exposure apparatus 500 shown in FIG. 9 is soconstructed that when the imaging lens unit (lens unit 514) is movedalong the optical path L, mirrors 510 and 512 are also moved to changethe optical path length, with a consequent change in the exposing ratioto permit size reduction or enlargement of the image to be formed. Thespot of reflected light focused in the exposure plane 518 has a certainwidth in the direction in which the light-sensitive material is scannedas indicated by arrow z. This width which is hereinafter sometimesreferred to as the "scan width" varies with the specific exposing ratioselected. If the slit 507 in the light source 506 is assumed to have awidth of 10 mm, the scan width is 10 mm for the exposing ratio 1:1, 20mm for the ratio 1:2, and 5 mm for the ratio 1:0.5. Hence, the width ofexposure slit 522 located in front of the exposure plane 518 is usuallyset to about 16-20 mm in a slit scanning exposure apparatus that has ascan width of 10 mm for an exposing ratio of 1:1 and that is capable ofexposing at ratios ranging from 1:0.5 to 1:2. However, if the exposureslit 522 has a width of 16 mm, the scan width becomes smaller than saidslit width when size-for-size or reduction exposure is to be performed,thereby creating a gap in the exposure slit 522 in either the upper orlower portion or both in the direction of scanning by reflected light.In the presence of such gaps, "flare" such as randomly reflected lightfrom the imaging lens unit or extraneous light will fall on the exposureplane 518 to produce an unsatisfactory image such as an unsharp image oran image with a blurred contour.

Modern versions of slit scanning exposure apparatus are often requiredto perform a special type of exposure, such as exposing only a selectedarea of a light-sensitive material with reflected light from a smalldocument and leaving the other areas unexposed, or exposing alight-sensitive material with only the light reflected from part of theimage on a document and leaving the other part of the image unprocessed.Following these operations, the unexposed areas are exposed and byperforming such multiple exposure, desired portions of more than oneimage are combined to form a single image. This "editing" procedure isdifficult to accomplish with the prior art slit scanning exposureapparatus unless masking or other extra steps are taken.

Including the first color filter assembly 536 and the second colorfilter assembly 538 used in the lens unit 514 shown in FIG. 10, all ofthe color filters used to adjust the quality of light in the prior artslit scanning exposure apparatus are so constructed that they areinserted into the optical path in a direction perpendicular to thescanning direction, or in a direction parallel to the slit length, withthe reflected light being adjusted in accordance with the amount inwhich a specific filter is inserted.

As a result of various studies they conducted in order to improve theprior art slit scanning exposure apparatus, the present inventors foundthat when color filters for adjusting the quality of light were insertedinto the optical path L in a direction parallel to the slit length as inthe prior art, uneven color formation occurred in the resulting image.As already mentioned, the quality of light is adjusted not only bychanging the type of color filter to be inserted into the optical path Lbut by varying the amount in which it is inserted. Hence, the rays oflight emerging from the color filter assembly will unavoidably containthe portion which has passed through the inserted color filter and theportion which has not. The light component which passed through theinserted color filter will have its quality adjusted before it falls onthe exposure position to expose the light-sensitive material, whereasthe component that has passed through the position where no color filterwas inserted will fall, totally unadjusted, on the exposure position toexpose the light-sensitive material.

In slit scanning exposure, scanning for exposure is performed along theshorter side of slit, namely, in a direction perpendicular to thedirection in which color filters are to be inserted into the opticalpath. Thus, not all surface of the light-sensitive material can beexposed with properly adjusted light but instead two differently exposedareas will occur on a single light-sensitive material, one area beingexposed with properly adjusted light and the other being exposed withyet to be adjusted light. Consequently, the image obtained will not haveuniform colors across the surface of the light-sensitive material butsuffers the problem of uneven color formation.

BRIEF SUMMARY OF THE INVENTION

The first object, therefore, of the present invention is to provide aslit scanning exposure apparatus that is capable of adjusting theexposure slit in front of the exposure plane in accordance with whateverexposing ratio is selected, that is capable of performing exposure in asatisfactory way by effectively safeguarding against the admission offlare toward the exposure plane, and that can be furnished, ifnecessary, with an editing capability such that multiple exposure isperformed by combining such special procedures as exposing only adesired area of a light-sensitive material with reflected light from theimage on a small document, or exposing a light-sensitive material withreflected light from the image on only a desired area of a document.

The second object of the present invention is to provide a slit scanningexposure apparatus of a type that adjusts the quality of light inaccordance with the amount by which a certain color filter is insertedinto the optical path and which is capable of forming an image that isfree from uneven colors but which insures uniform color shades in everypart of the image.

According to its first aspect, the present invention attains theabove-stated objects by a slit scanning exposure apparatus comprising anexposing light source, a plurality of mirrors by which the light emittedfrom said exposing light source and which is reflected from the image ona document moving relative to said exposing light source is reflectedtoward a predetermined exposure position, an imaging lens unit that actson the optical path of said reflected light and by which the image onsaid document is focused in said exposure position on a light-sensitivematerial that is being transported in synchronism with the speed atwhich the image on said document is scanned with said exposing lightsource, a pair of slit plates that are provided in front of saidexposure position and which are movable independently of each other inthe scanning direction, drive means for causing said pair of slit platesto move independently of each other, and control means for controllingsaid drive means in such a way that said pair of slit plates will moveindependently of each other in accordance with the area of saidlight-sensitive material to be exposed.

According to its second aspect, the present invention attains theabove-stated objects by a slit scanning exposure apparatus comprising anexposing light source, a plurality of mirrors by which the light emittedfrom said exposing light source and which is reflected from the image ona document moving relative to said exposing light source is reflectedtoward a predetermined exposure position, an imaging lens unit that actson the optical path of said reflected light and by which the image onsaid document is focused in said exposure position on a light-sensitivematerial that is being transported in synchronism with the speed atwhich the image on said document is scanned with said exposing lightsource, and at least one color filter that can be inserted into theoptical path of said reflected light in the scanning direction.

According to its third aspect, the present invention attains theabove-stated objects by a slit scanning exposure apparatus which in thesecond aspect of the present invention further includes a pair of slitplates that are provided in front of said exposure position and whichare movable independently of each other in the scanning direction, drivemeans for causing said pair of slit plates to move independently of eachother, and control means for controlling said drive means in such a waythat said pair of slit plates will move independently of each other inaccordance with the area of said light-sensitive material to be exposed.

In a preferred embodiment of the first and third aspect, said drivemeans comprises a rack formed on each of said slit plates, a gearmeshing with said rack, and a motor for driving said gear.

In another preferred embodiment of the first and third aspect, said slitplates are movable in synchronism with the speed at which saidlight-sensitive material is transported for scanning.

In still another preferred embodiment of the first and third aspect,said exposing light source and said plurality of mirrors form an imagingoptical unit of moving type which moves to perform scanning byilluminating said image on a document which is fixed.

In another preferred embodiment of the second and third aspect, saidcolor filter is provided between two lens groups in said imaging lensunit.

In still another preferred embodiment of the second and third aspect,said color filter consists of filters of the three primary colors.

In a further preferred embodiment of the second and third aspect, saidfilters of the three primary colors are a cyan, a magenta and a yellowfilter.

In yet another preferred embodiment of the second and third aspect, saidcolor filter is formed on a color filter plate and is inserted into theoptical path of said reflected light by a drive mechanism composed ofpins formed on opposite ends of said color filter plate, support membershaving guide grooves of a generally U or inverted U shape which are inrespective engagement with said pins, transmission members which arepivotally supported on fulcrums formed on the respective support membersand which have slits or elongated holes at one end which are inengagement with said pins, a drive member for causing the other end ofeach of said transmission members to pivot, and drive means for saiddrive member.

In a further preferred embodiment of the second and third aspect, saidcolor filter plate has two different color filters formed thereon.

In a further preferred embodiment of said two different color filtersare formed on two color filter plates, with at least one of said colorfilters on one color filter plate being different from the color filterson the other color

filter plate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic sectional view of a slit scanning exposureapparatus according to an embodiment of the present invention;

FIG. 2a to 2f are partial diagrammatic sectional views showing theoperation of a variable slit assembly incorporated in the slit scanningexposure apparatus of the present invention;

FIG. 3a and 3b are schematic views illustrating the method of performingpartial exposure with the slit scanning exposure apparatus of thepresent invention;

FIG. 4 is a diagrammatic sectional view of a slit scanning exposureapparatus according to another embodiment of the present invention;

FIG. 5 is a diagrammatic perspective view of an example of the lens unitto be used in the slit scanning exposure apparatus of the presentinvention;

FIG. 6a to 6c are diagrammatic front views of the first color filterassembly to be used in the lens unit shown in FIG. 5;

FIG. 7 is a diagrammatic front view of the second color filter assemblyto be used in the lens unit shown in FIG. 5;

FIG. 8 is a diagrammatic sectional view showing a silver halidephotographic copier to which a slit scanning exposure apparatusaccording to a still another embodiment of the present invention isapplied;

FIG. 9 is a diagrammatic sectional view of a prior art slit scanningexposure apparatus; and

FIG. 10 is a diagrammatic perspective view of an example of the lensunit applied to the prior art slit scanning exposure apparatus.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is described below in greater detail.

The slit scanning exposure apparatus of the present invention is chieflyintended to be used with image recording apparatus which records imageon light-sensitive materials. Light-sensitive materials with which thepresent invention may be employed include color or monochromatic silverhalide photographic materials, and non-silver halide photographicmaterials such as light-sensitive drums and thermographic materials. Theslit scanning exposure apparatus of the present invention may be appliedto various types of image recording apparatus including, for example,color or monochromatic silver halide photographic copiers, non-silverhalide photographic copiers, electrophotographic image recordingapparatus, silver halide photographic image recording apparatus, thermaltransfer image recording apparatus, ink-jet image recording apparatus,and those image recording apparatus which employ various otherlight-sensitive materials such as light- and pressure-sensitivematerials and photopolymeric materials.

In using the slit scanning exposure apparatus of the present invention,the image on a document may be scanned with either the light source orthe document platen being moved. In the description that follows, a slitscanning exposure apparatus that employs an optical system that performsimaging with the light source being moved is taken as a typical example.

To begin with, the first embodiment of the present invention depicted inFIGS. 1 to 3b is described below.

The slit scanning exposure apparatus according to the first embodimentof the present invention has a pair of slit plates that are located infront of the exposure plane of a light-sensitive material and that arecapable of moving independently of each other. During exposure, theindividual slit plates can be moved as the light-sensitive materialmoves in synchronism with the speed at which the image on the documentis scanned with an exposing light source. The spot of reflected lightfrom the document will vary in width in the scanning direction inaccordance with the specific exposing ratio selected but in the slitscanning exposure apparatus of the present invention, the slit width canbe adjusted in response to these variations in scan width, so in no casewill a gap be formed between the spot of reflected light and theexposure slit. Flare such as randomly reflected light from the imaginglens unit can thus be effectively prevented from falling on the exposureplane, to thereby insure the formation of a satisfactory imageirrespective of the exposing ratio selected.

Further, the slit scanning exposure apparatus of the present inventioncan be so constructed that when the exposure position on alight-sensitive material is designated by various means, the two slitplates are moved independently of each other to close or open theexposure slit in accordance with the designated exposure position.Hence, by combining this apparatus with region designating means such asa digitizer, a special operation, such as exposing only a selected areaof the light-sensitive material with reflected light from a selectedpart of the image on a document or exposing only a selected area of thelight-sensitive material with reflected light from the image on a smalldocument, can be performed. These techniques can be utilized to performmultiple exposure and edit a single image from the combination of two ormore documents.

The slit scanning exposure apparatus according to the first embodimentof the present invention is described below in greater detail withreference to FIGS. 1 to 3b.

FIG. 1 is a diagrammatic sectional view of the slit scanning exposureapparatus. In the slit scanning exposure apparatus (hereinaftersometimes referred to simply as a "scanning exposure apparatus") whichis generally indicated by 10 in FIG. 1, a document 14 is placed on aplaten 12 such as copy glass and is fixed in position by means of a topcover 13 and in association with the image on this document, alight-sensitive material A that is pressed against a glass plate 44 bymeans of a plate 42 in an exposing zone 40 and that is being transportedfor scanning purposes by means of transport rollers 46 and 48 in thedirection indicated by arrow z is exposed by slit scanning in exposureposition 40a.

The scanning exposure apparatus 10 outlined above consists basically ofthe following components: a light source unit having an exposing lightsource 16 and a first mirror 18; a mirror unit having a second and athird mirror 20 and 22; a lens unit 24 capable of moving back and forthalong the optical path L; a shutter 26; an image sensor 28; and a slitassembly 32 located just in front of a partition wall 30. The word"front" is used herein in connection with the direction in whichreflected light travels. The scanning exposure apparatus 10 ischaracterized in that the slit assembly 32 is a variable slit assemblycomposed of a pair of slit plates 34 and 36 which are capable of movingindependently of each other in the scanning direction (vertically asviewed in FIG. 1).

The light source unit is moved by certain means (not shown) across theunderside of the platen 12 in the scanning direction indicated by arrowx to illuminate the document 14 with the exposing light source 16. Thelength of the exposing light source 16 is substantially equal to thewidth of platen 12, which is the dimension taken in a directionperpendicular to the scanning direction. Two typical examples of theexposing light source 16 are a halogen lamp and fluorescent lamp. Thislight source is equipped with a reflector 38 to increase the efficiencyof light condensation and the reflector is provided with a slit 39 fordefining the width of reflected light from the document 14 in thescanning direction.

The light reflected from the document 14 (this light is hereinafterreferred to as "reflected light") passes through the slit 39 and isreflected by the first mirror 18 to be admitted into the mirror unit. Asalready mentioned, the mirror unit has the second mirror 20 and thethird mirror 22 and moves in the same direction as the light source unitat one half the speed of its movement in order to further reflect thereflected light to travel in a predetermined optical path L.

The lens unit 24 is the combination of imaging lenses and a device foradjusting the quantity and quality of reflected light. It comprises thefront group 50 and rear group 52 of imaging lenses, a first color filterassembly 54 composed of an unfiltered area, a cyan filter and magentafilter, a fixed diaphragm stop 56, a second color filter assembly 58composed of an unfiltered area, a cyan filter and a yellow filter, (thefirst color filter assembly 54, fixed diaphragm 56 and the second colorfilter assembly 58 are located between the front lens group 50 and therear lens group 52), and a variable diaphragm stop that is locatedbehind the rear lens group 52 and that is composed of a pair of plates60a and 60b.

The lens unit 24 to be used in the first embodiment of the presentinvention is not limited in any particular way and it may be the lensunit to be described hereinafter and which is shown in FIG. 5, as wellas a known lens unit, say, the lens unit shown in FIG. 10.

The lens unit 24 is constructed in such a way that it is capable ofmoving not only along the optical path L but also in a plane includingthe rays of reflected light in a direction perpendicular to the opticalpath L as required. The scanning exposure apparatus 10 performsenlargement exposure with the lens unit 24 being moved forward, andperforms reduction exposure with the lens unit moved backward.

The shutter 26 changes the direction of optical path L in such a waythat light is admitted either into the image sensor 28 or onto theexposing zone 40. This shutter is pivotally supported on a shaft 62 insuch a way that it moves either to the position indicated by a solidline in FIG. 1 or to the position indicated by a dashed line. Duringordinary exposure, the shutter 26 is retracted from the optical path Lto the position indicated by a solid line; during prescanning oradjustment for white balance, the shutter is inserted into the opticalpath L to the position indicated by a dashed line so that it furtherreflects the reflected light to be launched into the image sensor 28 viamirror 64.

The image sensor 28 is intended to perform photometry on such parametersas the quantity and quality of light during prescanning or adjustmentfor white balance. On the basis of the result of such photometricmeasurements, not only the type of color filters in the lens unit 24that are to be inserted into the optical path L and the amounts by whichthey are inserted but also the amount by which the quantity of light isto be adjusted with the variable diaphragm stop are determined and thenecessary adjustments are effected.

The scanning exposure apparatus 10 according to the first embodiment ofthe present invention has the variable slit assembly 32 positioned infront of the partition wall 30 that separates the apparatus from a zone(not shown) from which the light-sensitive material is to be supplied.The variable slit assembly 32 has a pair of slit plates 34 and 36 whichare capable of moving independently of each other in the directionindicated by arrow z, in which the light-sensitive material is to bescanned.

The operation of the variable slit assembly 32 is shown schematically inFIGS. 2a to 2f. The variable slit assembly 32 in the scanning exposureapparatus 10 according to the first embodiment of the present inventioncomprises a pair of slit plates 34 and 36, drive means which causesthese slit plates to move independently of each other in the scanningdirection (vertical direction as viewed in FIG. 2), and control meansfor controlling the movement of each slit plate.

In the example shown in FIG. 2, each of the slit plates 34 and 36 has arack formed on one end face in a direction perpendicular to the scanningdirection (directed into the paper). The rack formed on the slit plate34 engages a motor 72 via a gear 70 to form drive means, and the rackformed on the slit plate 36 engages a motor 76 via a gear 74 to formdrive means. When the motor 72 rotates, the slit plate 34 moves in thescanning direction independently of the slit plate 36 which is capableof moving in response to the rotation of the motor 76.

Each of the motors 72 and 76 is connected to a control circuit 78 whichcontrols the rotation of the respective motors.

In the scanning exposure apparatus 10 according to the first embodimentof the present invention, the use of the variable slit assemblydescribed above insures that during ordinary exposure, the width of thevariable slit assembly can be set to a value suitable for the scan widthof reflected light irrespective of whatever exposing ratio is selected,and this enables exposure to be performed in a satisfactory way withminimum admission of flare onto the exposure position 40a.

Further, by controlling the movement of individual slit plates 34 and36, a special operation, such as exposing only a selected area of thelight-sensitive material with reflected light from a selected part ofthe image on the document or exposing only a selected area of thelight-sensitive material with reflected light from the image on a smalldocument, can be performed. These techniques can be utilized to performmultiple exposure and edit a single image from the combination of two ormore documents.

The operation of the variable slit assembly in the case of exposing onlya selected area of the light-sensitive material is described below withreference to FIGS. 2a to 2f and FIGS. 3a and 3b. The followingdescription assumes the case where the scanning exposure apparatus 10shown in FIG. 1 is of a type that permits the document to be placed inregistry with the center line and where the document shown by 14a inFIG. 3a is placed on the platen 12 as shown in FIG. 3a, with the area14b (see FIG. 3b) being exposed at the ratio 1:1 with reflected lightfrom the image on the document 14a.

The document 14a is placed on the platen 12 as shown in FIG. 3a and thenthe area of the light-sensitive material A to be exposed is set to theregion delineated by straight lines a and b in FIG. 3b by means of adigitizer or some other region designating means that is connected tothe control circuit 78.

When a start button is pressed, the light-sensitive material A istransported in the direction indicated by arrow z. In this case, theslit plates 34 and 36 are held in close contact with each other at theirmeeting surfaces as shown in FIG. 2a, so the variable slit assembly 32works as a shutter to block the admission of light onto the exposureposition 40a.

When the exposure start position a in the designated area of thelight-sensitive material A is transported to the position where the twoslit plates are held in close contact with each other, motors 72 and 76start to rotate clockwise as viewed in FIG. 2. Then, as shown in FIG.2b, the slit plates which remain in close contact with each other attheir meeting surfaces to block the admission of light onto the exposureposition 40a, move backward in the scanning direction (hereinafterreferred to as "downward") with their meeting surfaces being kept inregistry with the exposure start position a.

When the exposure start position a (the surface where the two slitplates meet each other) is transported to the upper edge of the spot ofreflected light from the document, motor 72 stops rotating, causing theslit plate 34 to be stopped at the position where its lower end face isin registry with the upper edge of the spot of reflected light as shownin FIG. 2c. On the other hand, motor 76 continues to rotate and the slitplate 36, with its upper end face being in registry with the exposurestart position a, descends in synchronism with the transport of thelight-sensitive material A until the variable slit assembly 32 is openedto permit the light-sensitive material A to be exposed at the exposurestart position a with the reflected light from the document.

When the upper end face of the slit plate 36 moves to the lower edge ofthe spot of reflected light, motor 76 stops rotating and the slit plate36 also ceases to descend. Then, as shown in FIG. 2d, the variable slitassembly 32 is opened to an extent that matches the scan width, or thewidth of reflected light in the scanning direction, and thelight-sensitive material A can be exposed in a satisfactory mannerwithout admission of flare onto the exposure position 40a.

When the exposure proceeds and the light-sensitive material A istransported until the exposure end position b in the designated regionof said material comes into registry with the upper edge of the spot ofreflected light, motor 72 resumes its rotation in a clockwise directionand as shown in FIG. 2e, the slit plate 34, with its lower edge portionbeing in registry with the exposure end position a, descends insynchronism with the transport of the light-sensitive material A,thereby starting to close the variable slit assembly 32.

When the light-sensitive material A is transported until the exposureend position b comes into registry with the lower edge of the spot ofreflected light, the lower end face of the synchronously descending slitplate 34 will come into close contact with the upper end face of theslit plate 36 at their meeting surfaces to close the variable slitassembly 32 so that it works as a shutter to block the admission oflight onto the exposure position 40a. At the same time, motor 76 startsto rotate clockwise and, as shown in FIG. 2f, the slit plates, withtheir meeting surfaces remaining in close contact with each other toblock the admission of light onto the exposure position 40a, movedownward to the position where the slit plate 34 blocks completely theadmission of light onto the exposure position 40a.

When the exposure of light-sensitive material A is completed, motors 72and 76 start to rotate counterclockwise as viewed in FIG. 2 and the slitplates 34 and 36, with their meeting surfaces being kept in closecontact with each other, move upward to the position where the slitplate 36 blocks the admission of light onto the exposure position 40a(see FIG. 2a). This completes the procedure of preparation for the nextcycle of exposure.

Having the variable slit assembly 32 described above, the scanningexposure apparatus according to the first embodiment of the presentinvention is capable of exposing only a selected area of thelight-sensitive material A with reflected light from the document 14a.Since the areas of the light-sensitive material A other than region 14b(see FIG. 3b) remain unexposed similar procedures can be followed toexpose other areas of the light-sensitive material with reflected lightfrom other images and by performing this multiple exposure, a pluralityof images can be edited to form a single image.

If desired, similar procedures may be repeated to perform severalexposures with reflected light from the same image, thereby forming thesame image in many areas on a single light-sensitive material A.

In the example shown in FIG. 2, slits plates 34 and 36 are drivenseparately by motors 72 and 76 but the present invention is not limitedto this particular case alone and a single drive source comprising aclutch, gears, etc. may be used to render the two slit plates movableindependently of each other. The method of moving the slit plates alsois not limited to the racks formed on the respective slit plates andvarious other mechanisms may be employed as exemplified by the use ofvarious types of cams or the use of a drive shaft, a link, a belt and awire.

In the scanning exposure apparatus according to the first embodiment ofthe present invention, the movement of the two slit plates can becontrolled by various methods such as a sensor that is provided halfwayof the transport path of light-sensitive material A and which detectsits position to move a specific slit plate. In another method, themethod of moving each slit plate is predetermined in accordance withexposing ratio, the size of image to be formed, or other information andthese parameters are entered by the operator or measured with the imagesensor 28 to perform automatic control over the movement of the slitplates.

The foregoing description assumes that the light-sensitive material A isexposed across its entire region in the direction of its width(hereinafter referred to as the "widthwise direction") which isperpendicular to the scanning direction indicated by arrow x. Ifdesired, only a part of the surface of the light-sensitive material A inthe widthwise direction may be exposed by moving the lens unit 24 in aplane including the rays of reflected light and in a directionperpendicular to the optical path L, or by masking the unwanted areas.

The slit scanning exposure apparatus according to the first embodimentof the present invention has a variable slit assembly in front of,preferably in close proximity to, the exposure position of alight-sensitive material, which assembly consists of a pair of slitplates that are capable of moving independently of each other. Hence,the slit width of the variable slit assembly in front of the exposureposition can be adjusted to an optimum value that matches the width ofthe spot of reflected light from the document in the direction in whichit is scanning the light-sensitive material at a selected exposingratio. As a result, flare such as randomly reflected light from theimaging lens unit will not be admitted onto the exposure position andthe formation of a satisfactory image is insured.

Further, the slit plates of the variable slit assembly can be controlledto move independently of each other and this permits the performance ofa special operation such as exposing only a selected area of alight-sensitive material with reflected light from part of the image ona document, or exposing only a selected area of the light-sensitivematerial with reflected light from the image on a small document. If theexposure position on the light-sensitive material is designated by somesuitable means, the slit plates can be moved in association with thedesignated exposure position to either open or close the slit assembly.Thus, by using a digitizer or some other area designating means, thelight-sensitive material can be exposed with light reflected from aselected part of the image on a document or only a selected area of thelight-sensitive material can be exposed with reflected light from theimage on a small document.

By utilizing these techniques to perform multiple exposure, desiredparts of more than one document can be edited to form a single image onone light-sensitive material.

The second embodiment of the present invention is described below withreference to FIGS. 4-7.

The slit scanning exposure apparatus according to the second embodimentof the present invention has at least one color filter that can beinserted into the optical path of exposing light, which is adjusted bycontrolling the amount in which said color filter is inserted into saidoptical path. The color filter is inserted in a direction parallel tothe shorter side of the exposure slit, namely in the direction ofexposure by scanning. Thus, unlike the prior art slit scanning exposureapparatus in which color filters are inserted into the optical path in adirection parallel to the slit length (i.e., in a directionperpendicular to the direction of exposure by scanning), the apparatusof the present invention permits the entire surface of a light-sensitivematerial to be exposed with light that has been properly adjusted bymeans of color filters. Consequently, a satisfactory image that isuniform is color shades and which has no uneven colors can be formed byusing the slit scanning exposure apparatus according to the secondembodiment of the present invention. As in the first embodiment, theslit scanning exposure apparatus of the present invention may be of atype in which the light source is movable or of a type in which thedocument platen is movable.

The slit scanning exposure apparatus according to the second embodimentof the present invention is described below with reference to thepreferred examples shown in FIGS. 4-7.

FIG. 4 is a diagrammatic sectional view of a preferred example of theslit scanning exposure apparatus (hereinafter referred to as the"scanning exposure apparatus") according to the second embodiment of thepresent invention. The slit scanning exposure apparatus indicated by 80in FIG. 4 has essentially the same construction as the slit scanningexposure apparatus 10 shown in FIG. 1 except for the lens unit and theslit located in proximity with the exposing zone, so the constituentelements which are common to both drawings are identified by likenumerals and will not be described in detail.

As shown in FIG. 4, the apparatus according to the second embodiment ofthe present invention is characterized by the construction of colorfilter assemblies in the lens unit 82. The slit 84 located in proximitywith the exposing zone 40 may be a fixed slit or it may be variable asalready described in connection with the first embodiment of the presentinvention (the use of such a variable slit in the slit scanning exposureapparatus according to the second embodiment is a third embodiment ofthe present invention). If the slit 84 is of a fixed type, it may beformed as an aperture in the partition wall 30.

Like the lens unit 24 (see FIG. 1), the lens unit 82 used in the secondembodiment of the present invention is the combination of imaging lensesand a device for adjusting the quantity and quality of reflected lightand has the construction shown in FIG. 5. The lens unit 82 comprises thefront group 80 and rear group 88 of imaging lenses, a first color filterassembly 90, a fixed diaphragm stop 92, a second color filter assembly94 (these three components are arranged in the order written along theoptical path L of travelling light between the front lens group 86 andthe rear lens group 88), and variable diaphragm stop 96 that is locatedbehind the rear lens group 88 and which has a pair of plates 96a and96b.

The first color filter assembly 90 is such that a colorless andtransparent glass plate 100 having a cyan filter 100C and a yellowfilter 100Y formed thereon by evaporation or some other suitable methodis secured in a frame 91. Similarly, the second color filter assembly 94is such that a colorless and transparent glass plate 102 having a cyanfilter 102C and a magenta filter 102M formed thereon is secured in aframe 95.

The first color filter assembly 90 and the second color filter assembly94 are moved in the scanning direction, or in a direction parallel tothe shorter side of exposure slit 84, so as to insert either one of theassociated filters into the optical path L. The first color filterassembly 90 moves downward (as viewed in FIG. 5) in a direction parallelto the shorter side of the slit 84 (this way of movement is hereinafterreferred to simply as "downward"), whereas the second color filterassembly 94 moves upward in a direction parallel to the shorter side ofexposure slit 84 (this way of movement is hereinafter referred to simplyas "upward") so that a specific color filter in either filter assemblywill be inserted into the optical path L. The color filter assemblies 90and 94 will be elaborated later in this specification.

The fixed diaphragm stop 92 adjusts the quality of light and has acircular aperture 93 in the example shown in FIG. 5.

The variable diaphragm stop 96 located behind the rear lens group 88 iscomposed of a pair of plates 96a and 96b and a plate cam 98.

In the example shown in FIG. 5, two pins 104 provided on the rearwardface of the plate 96a and another two pins 106 provided on the rearwardface of the plate 96b are supported by being inserted into four obliquegrooves 108 formed in the plate cam 98. A rack 110 is also formed on theplate cam 98 and engages a stepping motor 116 via gears 112 and 114.

The variable diaphragm stop 96 is so constructed that when the steppingmotor 116 rotates clockwise, the plate cam 98 moves rightward (as viewedin FIG. 5) in a direction parallel to the length of exposure slit 84,whereupon the plates 96a and 96b depart from each other to increase theslit width. On the other hand, when the stepping motor 16 rotatescounterclockwise, the plate cam 98 moves leftward along the slit length,whereupon the plates 96a and 96b come closer to each other to decreasethe slit width.

FIG. 6a shows specifically an example of the first color filter assembly90 and the mechanism for driving it. As already mentioned, the firstcolor filter assembly 90 is such that the glass plate 100 having cyanfilter 100C and yellow filter 100Y formed thereon by evaporation or someother suitable method is secured in the frame 91. In the example shownin FIG. 6a, cyan filter 100C is formed in the upper left part of glassplate 100 whereas yellow filter 100Y is formed in the upper right partof said glass plate (the horizontal direction as viewed in FIG. 6acorresponds to the longitudinal direction of slit 84 shown in FIG. 5),and the two filters are separated by a distance equal to the "play" ofthe drive mechanism to be described later in this specification.

In the example shown in FIG. 6a, the aperture 93 in the fixed diaphragmstop 92 is circular, so if each of the cyan filter 100C and yellowfilter 100Y is a square of such a size that the aperture 93 is inscribedin it, the overall size of the color filter assembly 90 can be reduced.Pins 118a and 118b that are to engage the drive mechanism are providedin the left and right end portions, respectively, of the frame 91.

The drive mechanism for the first color filter assembly 90 comprisesbasically the following components: a support member 122a having a guidegroove 120a of a generally inverted U shape formed therein; a supportmember 122b having a similarly shaped guide groove 120b formed therein;a transmission member 126a pivotally supported on a fulcrum 124a formedon the support member 122a; a transmission member 126b pivotallysupported on a fulcrum 124b formed on the support member 122b; and adrive member 130 that engages both transmission members to drive them byrotation of a motor 128.

The support members 122a and 122b are secured by fastening means (notshown). Pin 118a is inserted into the guide groove 120a formed in thesupport member 122a, and pin 118b is inserted into the guide groove 120bformed in the support member 122b. This arrangement allows the frame 91to be supported in such a way that it is capable of vertical movementsalong guide grooves 120a and 120b.

As already mentioned, the guide groove 120a formed in the support member122a is an aperture having a generally inverted U shape, and it has alinear top portion that takes into account the play of the overall drivemechanism. The guide groove 120a is symmetric with respect to the centerline and its left half is of such a shape that the linear portion isfollowed by a quadrant of a circle having the same radius as theaperture 93, which in turn is followed by a downwardly extendingstraight line. Stated more specifically, the shape of the guide grove120a is such that when the pin 118a moving to the left comes out ofengagement with the linear portion of the guide groove 120a, the lowerleft corner of yellow filter 100Y descends along the circumference ofthe aperture 93 after passing by its highest point, and that when saidlower left corner descends to the leftmost part of aperture 93, itsubsequently drops in a vertical direction.

The right half of the guide groove 120a has such a shape that when thepin 118a moves to the right, the lower right corner of cyan filter 100Cwill move in a similar way. Hence, the distance between cyan filter 100Cand yellow filter 100Y is equal to the length of the linear top portionof guide groove 120a.

The play of the drive mechanism need not be provided in the guide groove120a in the present invention and if no play is provided, the distancebetween cyan filter 100C and yellow filter 100Y will inevitably becomezero. The guide groove 120b formed in the support member 122b has asimilar shape to the guide groove 120a.

In the example shown in FIG. 6a, lower fulcrums 124a and 124b are formedon the support members 122a and 122b, respectively, in the center oftheir lower portion. Transmission member 126a is pivotally supported onthe fulcrum 124a. A slit (elongated hole) 132a is formed in the upperpart of transmission member 126a and the already described pin 118a isinserted into this slit 132a. A pin 134a which is to engage the drivemember 130 is secured to the lower end portion of transmission member126a.

Slit 132a is formed parallel to the longitudinal direction oftransmission member 126a and has such a shape that pin 118a looselyfitted thereinto can move freely. This slit need only have a length thatpermits free movement of the frame 91 in vertical directions.

The transmission member 126b also has a similarly shaped slit 132b ofthe same size, as well as a pin 134b and is pivotally supported on thefulcrum 124b formed on the other support member 122b. Pin 118b isinserted into slit 132b.

In the example shown in FIG. 6a, slits 136a and 136b in the drive member130 through which pins 134a and 134b are to be inserted are formed in avertical direction with respect to pins 118a and 118b on the frame 91 insuch a way that the distance between slit 136a and pin 118a is equal tothe distance between slit 136b and pin 118b. The drive member 130 isbrought into engagement with transmission members 126a and 126b by meansof pins 118a and 118b. A rack 138 is formed on the drive member 130 andbrought into engagement with a motor 128 via a gear 140. Depending onthe direction in which the motor 128 rotates, the drive member 130 moveseither leftward or rightward to tilt both transmission members 126a and126b, causing pins 218a and 218b to move along guide grooves 120a and120b, respectively, so that either one of color filters descend alongthe circumference of the aperture 93 in the fixed diaphragm stop 92until it is inserted into the optical path L.

A pulse motor, a stepping motor or any other suitable motor mayadvantageously be used as the motor 128.

The operation of the first color filter assembly 90 and that of themechanism for driving it are described below. First, the case ofinserting yellow filter 100Y into the optical path L is explained. Asshown in FIG. 6b, motor 128 rotates counterclockwise and drive member130 moves to the right by an amount that is proportional to the amountof motor rotation. When the drive member 130 moves to the right,transmission members 126a and 126b in engagement with the drive membervia pins 134a and 134b pivot counterclockwise about the fulcrums 124aand 124b, respectively, by an amount proportional to that of themovement of the drive member.

As a result of pivoting of transmission members 126a and 126b, the driveforce is transmitted to pins 118a and 118b inserted into slits 132a and132b, respectively, causing the frame 91 to move to the left.

Since pins 118a and 118b are also in engagement with the guide grooves120a and 120b in the support members 122a and 122b, respectively, thesepins will move along the guide grooves 120a and 120b. the guide grooves120a and 120b have the shape already described above. Thus, as long aspins 118a and 118b move in the linear portions of guide grooves 120a and120b, the frame 91 continues to make a translational movement to theleft, and when they come out of engagement with those linear portions,the lower left corner of yellow filter 100Y moves down along theperiphery of the aperture 93 and yellow filter 100Y is inserted into theoptical path L by closing the upper portion (in a direction parallel tothe shorter side of the exposure slit) by an amount proportional to thatof the rotation of motor 128.

As already mentioned, the frame 91 moves (or yellow filter 100Y isinserted) downward in a vertical direction after pins 118a and 118b comeout of engagement with the curved portions of guide grooves 120a and120b.

If the operator wants to insert cyan filter 100C into the optical pathL, the following procedure is taken. Motor 128 is rotated clockwise anddrive member 130 moves to the left to cause transmission members 126aand 126b to pivot clockwise. As shown in FIG. 6c, pins 118a and 118bthen move along guide grooves 120a and 120b, respectively, until cyanfilter 100C is inserted into the optical path L by closing the aperture93.

FIG. 7 shows specifically an example of the second color filter assembly94 and the mechanism for driving it. Like the first color filterassembly 90, the second color filter assembly 94 is such that colorlessand transparent glass plate 102 having cyan filter 102C and magentafilter 102M formed thereon by evaporation or some other suitable methodis secured in a frame 95. In the example shown in FIG. 7, cyan filter102C is formed in the lower left part of glass plate 102 whereas magentafilter 102M is formed in the lower right part of said glass plate.

The mechanism for driving the second color filter assembly 94 is similarin construction to the mechanism for driving the first color filterassembly 90 and comprises basically the following components: a supportmember 152a having a guide groove 150a; a support member 152b having aguide groove 150b; a transmission member 156a pivotally supported on afulcrum 154a formed on the support member 152a; a transmission member156b pivotally supported on a fulcrum 154b formed on the support member152b; and a drive member 160 that engages both transmission members todrive them by rotation of a motor 158.

The second color filter assembly 94 shown in FIG. 7 and the mechanismfor driving it need not be described in great detail since they areessentially the same as the already described first color filterassembly 90 and its associated drive mechanism except that the positionof a motor 158 in engagement with the drive member 160 differs from themotor 128 and that the combination of color filter assembly and itsdrive mechanism is inverted. It should however be noted that the firstcolor filter assembly 90 is operated by inserting either one of theassociated color filters from above into the optical path L, whereaswith the second color filter assembly 94, either one of the associatedcolor filters is inserted from below into the optical path L, asspecifically described below. When motor 158 rotates clockwise, thedrive member 160 moves to the left and each of the transmission memberspivots clockwise, whereupon pins 162a and 162b ascend rightward alongtheir guide grooves 150a and 150b until cyan filter 102C partly closesthe aperture 93. Conversely, when motor 158 rotates counterclockwise,the drive member 160 moves to the right and each of the transmissionmembers pivots counterclockwise, whereupon pins 162a and 162b ascendleftward along their guide grooves 150a and 150b until magenta filter102M partly closes the aperture 93.

In the slit scanning exposure apparatus according to the secondembodiment of the present invention, either one of the color filters ineach of the first and second color filter assemblies is inserted intothe optical path L in the scanning direction, namely, in a directionparallel to the shorter side of the exposure slit. Thus, compared to theprior art version in which color filters are inserted into the opticalpath in a direction parallel to the slit length, the slit scanningexposure apparatus of the present invention is capable of forming animage of better quality that is free from unevenness in colors.

In the second embodiment of the present invention, each of the colorfilter assemblies is driven by the link mechanism described above butthis is not the sole example of the drive mechanism for the color filterassemblies and it may be replaced by various other means for causingmovements in x- and y-directions, such as a rack-and-pinion, a drivescrew/travelling nut, and the combination thereof. Motor and other drivesources that are to be used need not be one in number and needless tosay, more than drive source may be employed.

As described above, the slit scanning exposure apparatus according tothe second embodiment of the present invention is so constructed thatcolor filters for adjusting the quality of reflected light from adocument are inserted into the optical path in a direction parallel tothe shorter side of the exposure slit. Hence, the entire surface of thelight-sensitive material A can be exposed with light that has beenappropriately adjusted by color filters and this contributes to theformation of a satisfactory image across the light-sensitive material Awith uniform color shades and in the absence of any uneven colors.

The slit scanning exposure apparatus according to the second aspect ofthe present invention has at least one color filter that can be insertedinto the optical path of exposing light, which is adjusted bycontrolling the amount in which said color filter is inserted into saidoptical path. The color filter is inserted in a direction parallel tothe shorter side of the exposure slit, namely in the direction ofscanning for exposure. Thus, unlike the prior art slit scanning exposureapparatus in which color filters are inserted into the optical path in adirection parallel to the slit length (i.e., in a directionperpendicular to the direction of scanning for exposure), the apparatusof the present invention permits the entire surface of a light-sensitivematerial to the exposed with light that has been properly adjusted bymeans of color filters. Consequently, a satisfactory image that isuniform in color shades and which has no uneven colors can be formed byusing the slit scanning exposure apparatus according to the secondembodiment of the present invention.

A slit scanning exposure apparatus according to the third embodiment ofthe present invention is essentially the same as the slit scanningexposure apparatus according to the second embodiment of the presentinvention except that the slit provided in proximity with the exposureposition is formed by a variable slit assembly of the type used in theslit scanning exposure apparatus according to the first embodiment ofthe present invention. In other words, the slit scanning exposureapparatus according to the third embodiment of the present invention iscomposed of the combination of the already described first and secondembodiments and hence need not be explained in detail.

The slit scanning exposure apparatus according to the third embodimentof the present invention is capable of producing an image of highquality that is free from unevenness in colors, that has uniform colorshades, that is sharp in the absence of blurred contour due to flare,and that is characterized by satisfactory color and densityreproduction. Further, the apparatus is simple in construction and yetis capable of editing a plurality of document images to form theabove-described high-quality image on a single print.

FIG. 8 shows a silver halide photographic copier incorporating the slitscanning exposure apparatus according to the third embodiment of thepresent invention. The silver halide photographic copier (hereinafterreferred to simply as "copier") generally indicated by 200 in FIG. 8consists of three basic units, a light-sensitive material supply unit202 on the right side, an exposing unit 204 in the upper part, andprocessing unit 206 in the lower part.

The exposing unit 204 comprises frame 205 having incorporated thereinthe slit scanning exposure apparatus according to the third embodimentof the present invention. In other words, the slit scanning exposureapparatus incorporated in the frame 205 is essentially the same as theapparatus according to the second embodiment of the present inventionwhich is indicated by 80 in FIG. 4 except that slit assembly 84 isreplaced by the variable slit assembly 32 in the apparatus according tothe first embodiment of the present invention which is indicated by 10in FIGS. 1-3. Hence, the components common to the three embodiments areidentified by like numerals and will not be described in detail.

The light-sensitive material supply unit 202 comprises a frame 208having in its interior the transport path of light-sensitive materialsand a pair of detachable magazines 210 and 212 stacked one on top of theother. Rolls of light-sensitive materials 214 and 216 are placed in themagazines 210 and 212, respectively, and they are withdrawn from therespective magazines to be transported through the supply unit 202. Inone example, light-sensitive material 214 may be optimal for the purposeof copying color printed documents, and 216 may be optimal for copyingcolor photographic document.

Provided ahead of the magazine 210 are transport rollers 218 forwithdrawing light-sensitive material 214, which are followed by a cutter220 for cutting the light-sensitive material 214 to a predeterminedlength.

Light-sensitive material transport guides 222, 223 and 224 and transportrollers 226 and 228 are provided between the cutter 220 and the exposingzone 40 so as to guide a predetermined length of light-sensitivematerial 214 to the exposing zone 40. The exposing zone 40 is an areafor defining the exposure position 40a in association with thelight-sensitive material 214. In this exposing zone 40, a glass plate 42is fixed facing the slit scanning exposure apparatus 10 in the exposingunit 204 and a pressure plate 44 is pressed against the glass plate 42.

A pair of transport rollers 46 are provided upstream (above) theexposing zone 40 whereas a pair of transport rollers 48 are provideddownstream (beneath) said exposing zone. Further below the exposing zone40 is provided a transport guide 230 which guides the exposedlight-sensitive material 214 downwardly in a vertical direction. Achange guide 234 for changing the direction of the transport path oflight-sensitive material 214 (or 216) in such a way that it is fed intothe processing unit 206 via a branching transport guide 232 is providedhalfway down the transport guide 230.

Magazine 212 placed below the magazine 210 is furnished with transportrollers 236 and a cutter 238 in association with the light-sensitivematerial 216 and they are followed by transport guides 240 and 241 andtransport rollers 242 so that the light-sensitive material 216 isconveyed to the transport guide 222.

The processing unit 206 consists of a processing zone 244 and a dryingzone 246. The processing zone 244 contains in it a sequence of adeveloping tank 248, a bleach and fix tank 250 and washing tanks 252 and254. These tanks are filled with processing solutions that performdevelopment, bleaching, fixing and washing on light-sensitive material214 (or 216), which is then supplied into the drying zone 246. Thelight-sensitive material 214 (or 216) emerging from the washing tank 254is dried in the drying zone 246 and hence fed to a receiving tray 256.

The copier 200 incorporating the slit scanning exposure apparatusaccording to the third embodiment of the present invention is operatedas follows in order to copy a document in the ordinary mode (i.e., allthe image on the document 14 is copied on the entire surface oflight-sensitive material A). First, document 14 is placed on the platen12 and the top cover 13 is closed. Then, a specific exposing ratio isselected and the start button (not shown) on the copier 200 is pressed,whereupon exposing light source 16 turns on and the light source unitstarts a scanning operation (prescanning is started). On this occasion,the slit plates 34 and 36 of the variable slit assembly 32 are held inclose contact with each other at their meeting surfaces and hence theslit assembly 32 works as a shutter.

Reflected light from the document 14 is reflected by mirror 18 andfurther reflected by mirrors 20 and 22 in the mirror unit which move inthe same direction as the light source unit at one half the speed of itsmovement. The so reflected light travels along the optical path L,passes through the lens unit 82 and is reflected by the shutter 26 to beadmitted into the image sensor 28, where image information is read toset conditions for exposure modification.

After completion of this prescanning operation, the light source unitand the mirror unit are returned to the position where the scanning wasstarted.

The variable slit assembly is operated by the associated motors toadjust the slit width to an optimum value that matches the scan width ofreflected light at the selected exposing ratio. In the lens unit 82, thefirst color filter assembly 90 and the second color filter assembly 94are operated in the manner described in connection with the secondembodiment and either one of the associated color filters is insertedinto the optical path L in a direction parallel to the shorter side ofthe exposure slit 84 in accordance with the preset conditions forexposure modification. The variable diaphragm stop 96 is also adjustedto provide an aperture that matches the preset conditions for exposuremodification.

While prescanning and adjustments of the color filters and the diaphragmstop are being performed, the light-sensitive material which isnecessary for copying a document of interest is selected. For example,if the document 14 is a color photographic original, light-sensitivematerial 216 is selected. When a transport motor (not shown) is driven,transport rollers 236 and 242 deliver the light-sensitive material 216by a predetermined length and is cut to the necessary length by means ofthe cutter 238. Upon further driving of the transport motor, thelight-sensitive material 216 is supplied to the exposing zone 40 andpauses just in front of the exposure position 40a. When the shutter 26pivots to the position indicated by a solid line, it becomes possible toperform exposure and the light source unit starts the operation for mainscanning of the document 14. At the same time, transport rollers 46 and48 in the exposing zone 40 start to transport the light-sensitivematerial 216 for scanning in synchronism with the scan speed of thelight source unit. During the main scanning operation, light emittedfrom the exposing light source 16 in the light source unit and which hasbeen reflected by mirror 18 is further reflected by mirrors 20 and 22which move in the same direction as the light source unit at one halfthe speed of its movement. The reflected light is then adjusted bypassage through the lens unit 82 that has been properly adjusted interms of color filters and aperture. The light thus adjusted passesthrough the slit in the variable slit assembly located in front of thepartition wall 30 and is focused at the exposure position 40a to exposethe light-sensitive material 216 which is being transported for scanningin synchronism with the light source unit by means of roller pairs 46and 48.

Since the copier 200 incorporates the slit scanning exposure apparatus80 according to the second embodiment of the present invention, any oneof the color associated filters is inserted into the optical path L inthe scanning direction, namely in the direction parallel to the shorterside of the exposure slit and this insures that the entire surface ofthe light-sensitive material 216 is exposed with the properly adjustedlight without causing any unevenness in colors.

Further, the copier 200 uses a slit assembly which is of the same typeas the variable slit assembly 32 used in the slit scanning exposureapparatus 10 in accordance with the first embodiment of the presentinvention and this variable slit assembly is capable of producing anoptimum exposure slit that matches the scan width of reflected lightfrom the document. Thus, exposure can be performed in a satisfactory waywith minimum admission of flare onto the exposure position 40a.

As the exposure proceeds, the light-sensitive material 216 between thetransport rollers 46 and 48 is moved downward through the transportguide 230. In this instance, the change guide 234 does not act on thetransport path of the light-sensitive material 216 being supplied fromthe exposing zone 40 and said material moves downward vertically throughthe transport guide 230.

When the process of exposure is completed, the shutter 26 pivots to theposition indicated by a dashed line in FIG. 8 and blocks the opticalpath of reflected light. Then, all of the transport rollers change thedirection of their rotation and the exposed light-sensitive material 216ascends the transport guide 230 and part of it is supplied into thetransport guide 224.

The transport of the light-sensitive material 216 in the reversedirection continued until its leading edge comes upstream of the changeguide 234. Thereafter, all of the transport rollers are caused to rotatein the same forward direction as they did previously to transport thelight-sensitive material 216. On this occasion, the change guide 234acts on the transport path of the light-sensitive material 216 so thatits leading edge will be delivered to the branching transport guide 232.As a result, the leading edge of the light-sensitive material 216 passesby the branching transport guide 232 to be forwarded to the processingzone 244 in the processing unit 206.

The exposed light-sensitive material 216 which has been sent into theprocessing zone 244 is developed in the developing tank 248, bleachedand fixed in the bleach and fix tank 250 and washed thoroughly in thewashing tanks 252 and 254. The light-sensitive material emerging fromthe washing tank 254 is fed into the drying zone 246 where it is driedand thence delivered to the receiving tray 248.

The above-described copying procedure produces an image of high qualitythat is free from unevenness in colors, that has uniform color shades,that is sharp in the absence of blurred contour due to flare, and thatis characterized by faithful color and density reproduction.

While the slit scanning exposure apparatus of the present invention hasthe construction described on the foregoing pages, it should beunderstood that the present invention is not limited to the threeembodiments described above and that various improvements and designmodifications are possible without departing from its spirit and scope.

What is claimed is:
 1. A slit scanning exposure apparatus, comprising; an exposing light source, a plurality of mirrors by which light emitted from said exposing light source and reflected from an image on a document moving relative to said exposing light source is reflected toward a predetermined exposure position, an imaging lens unit which acts on an optical path of said reflected light and by which the image on said document is focused at said exposure position on a light-sensitive material, said material being transported in synchronism with the speed at which the image on said document is scanned with said exposing light source, a pair of slit plates provided in front of said exposure position and movable independently of each other in the scanning direction, means for driving said pair of slit plates independently of each other, and control means for controlling said drive means so that said pair of slit plates will move independently of each other in accordance with the area of said light-sensitive material to be exposed.
 2. A slit scanning exposure apparatus according to claim 1 wherein said drive means comprises a rack formed on each of said slit plates, a gear meshing with said rack, and a motor for driving said gear.
 3. A slit scanning exposure apparatus according to claim 1 wherein said slit plates are movable in synchronism with the speed at which said light-sensitive material is transported for scanning.
 4. A slit scanning exposure apparatus according to claim 1 wherein said exposing light source and said plurality of mirrors form an imaging optical unit which moves to perform scanning by illuminating said image on a document which is fixed.
 5. A method for exposing a selected area of a light sensitive material defined between an exposure start position and an exposure end position with a light reflected from a selected area or all of an image on a document by using a slit scanning exposure apparatus comprising,an exposing light source; a plurality of mirrors by which a light emitted from said exposing light source and which is reflected from said image on said document moving relative to said exposing light source is reflected toward a predetermined exposure position; an imaging lens unit that acts on an optical path defined by the reflected light and by which said image on said document is focused in said exposure position on said light-sensitive material which is being transported in synchronism with the speed at which the image on said document is scanned with said exposing light source; a pair of an upstream and a downstream slit plates which are provided in front of said exposure position and which are movable independently of each other in the scanning direction of the light-sensitive material to define a slit whose width is adjustable in accordance with exposing ratio such that said light-sensitive material is exposed with the reflected light which passed through said slit; drive means for moving said pair of slit plates independently of each other; and control means for controlling said drive means; comprising the step of, moving said pair of slit plates in the scanning direction of the light-sensitive material while they are held in close contact with each other at their meeting surface such that said meeting surface is in register with the exposure start position of said light-sensitive material until said meeting surface of said slit plates and said exposure start position of said light-sensitive material are in register with upstream edge of said optical path defined by said reflected light whose width is determined by the selected exposure ratio; stopping said upstream slit plate with its downstream end face in register with said upstream edge of said optical path, while said downstream slit plate continues its movement with its upstream end face in register with said exposure start position of said light-sensitive material to enlarge the slit defined between said upstream and said downstream slit plates until said upstream end face of said downstream slit plate is in register with downstream edge of said optical path defined by said reflected light; stopping said downstream slit plate with its upstream end face in register with said downstream edge of said optical path such that the slit has a width equal to that of said optical path until said exposure end position is in register with said upstream edge of said optical path; and moving said upstream slit plate in the scanning direction with its downstream end face in register with said exposure end position, while said upstream end face of said downstream slit plate is kept in register with said downstream edge of said optical path, to narrow the slit formed between said upstream and said downstream slit plates until said downstream end face of said upstream slit plate becomes in close contact with the upstream end face of said downstream slit plate to close the slit. 